The location of the log files produced by the Visual Studio Plugin can be found (and changed) on the "Logging" tab inside the "Options" window. To navigate to this window, select "Tools" and "Options" from the Visual Studio menu:

In the tree view on the "Options" window navigate to "Source Control" and "Logging":

The path to the log files can be found in the "Logfile path" field at the top. If you wish to store your log files in a different location, click the "..." button to the right of this field and navigate to the folder you prefer to use. Once you have completed your settings on this window, click the "OK" button to confirm and close the window, and then close and restart Visual Studio for your changes to take effect.